According to Apple, today's update was only incremental as it "just" added support for iOS 6 and iDevices that support said OS. The big update, which isn't coming until October, may or may not upgrade the encoder that they use. So I too am curious to see why things are a little different with this version of iTunes.

There was a format change of ALAC magic cookie on the new CoreAudioToolbox (7.9.8.1).New version returns the same format as the open sourced ALAC encoder, which is documented in ALACMagicCookieDescription.txt.Probably this update was done to make them consistent.

I reencoded an album earlier encoded with CoreAudio 7.9.7.9 and the bitrate of newer CoreAudio is slightly lower.Also I have made a spectral views of encoded audio short part, they are slightly different. Any conclusion which snapshot could be better?

I don't think much can be said other than the results that were found conducting that test. It might be all for not though since iTunes 11 is about a month away from being released. Even then, that might not change anything with the encoder that Apple is implementing. I have my reservations about upgrading to iTunes since it appears they are getting rid of the list view of an entire library but that is a different discussion.

If I understand good then audio data is related to apple's encoding library not to qaac.Although I think there's little difference from previous version (compare bitrates and spectral graphs between versions)

Core Audio Toolbox was changed between those 2 versions, so what are you implying that I'm doing wrong here?

Well, like you said it was wrong, two versions of qaac don't change/mean anything for the decoder but now you've changed the reply and of course it makes the difference, the DLL from iTunes/QuickTime was different.

Core Audio Toolbox was changed between those 2 versions, so what are you implying that I'm doing wrong here?

Well, like you said it was wrong, two versions of qaac don't change/mean anything for the decoderbut now you've changed the reply and of course it makes the difference, the DLL from iTunes/QuickTime was different.

Just for the record:Underlined is your assumption of what I was talking about (I have no idea why you or how you would assume that... because it's obviously very very very wrong)Bolded is untrue.

I was just telling you that the DLL (CoreAudioToolbox.dll) is what matters for the encoding of AAC with QAAC, based on what you said here: "TVBR 91 appears to have no difference between qaac 1.39 and 1.41."

Also yes, you didn't change your reply, you changed your statement, correcting what you said before and saying: "Core Audio Toolbox was changed between those 2 versions". Of course the quality was going to be different, not because of QAAC though.

And talking about the topic again, it's funny higher encoding result in slightly smaller files, I just encoded at -V36 for a project and the files with 7.9.8.1 are bigger, Apple may have improved the quality at lower bitrates?

IgorC, I can try but I promise you right now I will not hear anything different. AAC is so good I don't even notice anything from -V54 to Lossless, these little changes they are doing now are not for us I'm sure but for some kind of encoder optimization.

I don't know if this means anything, but I converted an album back in june *using sound forge izotope to downsample and quicktime pro to encode*

I use tvbr, and granted there's a new itunes update and version of sound forge izotope since then *but not a new qt update*, I rencoded the album again with the same process and the bitrate between the two are dramatically different.

Here's an example

SongBefore 96kbps After 89

Song 2Before 106 After 100

Song 3

Before 117 After 101

Song 4Before 145 After 147

It's perplexing really, there's no consistency to the difference in bitrates between the 2 different encodes, the settings are exactly the same, and wondering possibly if it were an error I deleted the new encode and re-encoded all over gain twice, and the results are exactly the same. Using replaygain, the peaks are different too, quicktime uses core audio I believe, but I have no idea if it's that or the soundforge update *which updates the izotope converter too*.

I don't think much can be said other than the results that were found conducting that test. It might be all for not though since iTunes 11 is about a month away from being released. Even then, that might not change anything with the encoder that Apple is implementing. I have my reservations about upgrading to iTunes since it appears they are getting rid of the list view of an entire library but that is a different discussion.

List view will still be there, slightly different but it's still there.

What this tells me is the tweaks on coreaudio must've directly effected quicktime too, because it hasn't been updated in months but I'm already seeing a difference in bitrates.

Stuff that will be 139 will become 127, 130 will become 114, etc...

Some songs will show an increase in bitrate by like 4, but the drastic difference is in the bitrate drop.

I've used quicktime for a few years and this is the most drastic change in bitrate I've seen.

An album that was 56.3mb before now became 53mb.

Now, these albums I'm comparing are my personal needledrops and as I've mentioned before sound forge has been updated also *I downsample with izotope*, however in my experience downsampling in the past after the update while the peaks do change in the files the bitrates stay virtually the same. So I think this is all coreaudio at work...